


Blood and Darkness

by ruff_ethereal



Series: Blood and Darkness [1]
Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Aged-Up Character(s), Alternate Universe - Demons, Alternate Universe - Supernatural Elements, Blood Drinking, Blood Kink, Dead Dove: Do Not Eat, Demon Byleth, F/F, Menstrual Sex, Oral Sex
Language: English
Status: Completed
Published: 2019-11-22
Updated: 2019-11-22
Packaged: 2021-02-17 22:55:02
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,183
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21517804
Author URL: https://archiveofourown.org/users/ruff_ethereal/pseuds/ruff_ethereal
Summary: The demon Byleth attempts a rather unorthodox and intimate solution to her monthly need for blood, with her mistress Edelgard's help.
Relationships: Edelgard von Hresvelg/My Unit | Byleth
Series: Blood and Darkness [1]
Series URL: https://archiveofourown.org/series/1698073
Comments: 7
Kudos: 160





	Blood and Darkness

**Author's Note:**

> As per the times and her lifestyle, Edelgard is unshaved between her legs. Sorry if that bothers you.
> 
> Also, this work _was_ inspired by three different works and authors, but... I don't want to directly link them to this unholiness.

In hindsight, Edelgard probably should have just set her bed on fire.

It would have been so much easier to explain, and so much less awkward and stressful than the scenario she found herself in now: laying nearly naked on her blood-soaked sheets, staring at a horrified Dorothea at the doorway.

"E-Edie…!" Dorothea stammered, her eyes wide, her voice and body shaking, just barely keeping herself together. "What in the world happened?!"

* * *

_Earlier that day…_

It was that time of the month again.

Byleth had done every single thing she could to delay it, attempted yet more questionable and curious methods to try to stop it altogether, but like the moon, it never failed to show itself again after a period of disappearance.

"Blood..." she whispered.

 _Human_ blood, to be precise, and preferably extracted directly from a healthy and young individual. There was no more fooling her Thirst, not with chocolate, pig's blood, or tomato juice. And Byleth needed it soon, or _all_ of Enbarr was going to have some _serious_ problems.

Normally, Hubert would have already helped sate her Thirst long before she felt it, but he was still off on official business, and wasn't likely to return any time soon. And with everyone else being ignorant of Byleth's demonic nature and the _grimmer_ aspects of it, there was only one person to turn to:

Edelgard.

Byleth sighed as she stood up and walked into the shadows behind her. "As your mistress, I take full responsibility for your actions, your needs, and your desires," Edelgard had told her, shortly after she had summoned Byleth. "Whatever it is, simply come to me, and it will be arranged for, and personally so if required."

As Byleth began to melt into the darkness, she thought of all the paperwork and meetings Edelgard had been dealing with these past few weeks, how little and how uneasily she had been sleeping, all the brews she was consuming to keep herself awake and alert.

"Maybe I should just go feed on some bandits," Byleth thought as she opened her mind's eye, began to visualize the nearby mountains.

Another memory of Edelgard interrupted her: "I don't _care_ if you thought it would be a good idea, or if the aftermath was ultimately for the better—you are my _servant_ , the most dangerous _weapon_ I have in my arsenal, and you _will_ be unleashed on my command, _and my command alone!"_

Like a stone had been hurled straight into a calm pond, Byleth's mental image broke in an explosion of ripples. As she focused again, it was replaced by a vision of Edelgard, her features so clear, so detailed, and complete it was like she was standing before the woman herself—and in moments, Byleth was, albeit partly incorporeal, and only visible and audible to her.

"Edelgard?" Byleth asked. She had meant to stay hidden, wait for Edelgard to give her one of the signals, then she smelled something that set her whole being alight:

Blood—Edelgard's blood.

In an instant, Byleth completely materialized, fingers transforming into razor-sharp claws, her eyes turning to slits, hunching over in a predatory stance as her senses went into overdrive.

Edelgard screamed.

_Thwack!_

Something struck Byleth on the head. She didn't even have time to figure out what it was, as Edelgard shrieked, "Get out! Get out! _Get out!_ I'm _indecent!"_

Byleth blinked. "Oh," she thought.

She turned to smoke just before a bottle of scented oil struck her. She surged over to Edelgard's desk, opened the lid of an ornate urn, went inside it, and shut it on herself. An unknown amount of time later, Edelgard opened it up, Byleth seeped out and rematerialized before her with her head down.

The now fully-dressed Edelgard sucked in a deep breath, and let it go slowly. "I am assuming you had a _very_ good reason to suddenly appear in my room without warning?"

Byleth looked up and nodded. "Blood," she said.

Edelgard groaned and rolled her eyes. She scowled, then paused, her eyes widening. "… Ah, I take it your Thirst has returned?"

"Yes," Byleth replied, nodding again. "I smelled your blood in the air earlier, too. Did you injure yourself?"

Edelgard shook her head. "I did not."

"Then why--?" Byleth stopped as she smelled blood again.

She had been in the thick of so many battlefields, she knew _exactly_ the scent of blood spilled by violence. But while this latest whiff was _undeniably_ fresh, it couldn't _possibly_ have been from a wound or injury.

Byleth looked up, found the normally serious and composed Edelgard suddenly staring intently to the side, her cheeks flushed red. "Edelgard…?" Byleth asked.

" _Yes, that_ has returned for me, also," Edelgard grumbled. "For your information, I was trying to cleanse myself earlier, and because it has been _exceptionally_ strong this month, I was forced to use several rags to soak up the blood. I have had them removed when the servants investigated the commotion earlier."

“I see,” Byleth said. "My apologies, Edelgard."

Edelgard waved her off. "You were acting as any decent retainer would if they sensed their master was in danger," she said as she headed to her writing desk. "Let's focus on more pertinent matters, like how we are to keep you from becoming a ravenous beast preying on anyone with a pulse." She sighed as she sat down, then pulled out a journal from a hidden compartment. "Damn it, I really should have sent you and Hubert together..."

"I actually have an idea of how to solve this, if you would like to hear it," Byleth said as she strode over.

"It had better not involve murder!" Edelgard said as she paged to Byleth's section. "We have overused such methods these past few months," she said as she grabbed a writing quill, dipped it in a nearby inkwell.

"It doesn't involve murder," Byleth said as she stood to one side of Edelgard.

"And instead…?" Edelgard asked, turning to look at Byleth.

"I'll drink your blood," Byleth replied.

Edelgard blinked, then sighed. "Byleth, you of all people in this castle should that I've been run nearly ragged these past few weeks… more likely than not, you'll be left unsatisfied, I'll be left severely weakened, and the entire Empire vastly worse off, also."

"I didn't mean by drinking from your veins," Byleth said.

Edelgard looked confused, before realization dawned on her. Her writing quill slowly dropped from her hand, a vast array of emotions played out on her face, until finally settling on disbelief, her gaze hard, her mouth set in a straight line. "You're joking," she said flatly.

"I am not a jester, I don't kid," Byleth replied.

Edelgard sucked in a deep breath, planted her hands on her desk, and slowly stood up. She calmly turned to Byleth, looked her in the eyes, and said, "Byleth: we cannot do this."

"Why not?" Byleth asked.

"Why not?" Edelgard spat, her face contorting in anger. "Why not…? Why not?!”

"Yes, why not?" Byleth asked, nodding.

Edelgard looked like she was about to scream at the top of her lungs, before she pinched her nose, and turned sharply away from Byleth. After several moments and many deep, slow breaths, she turned back to her, and said, "Byleth, I know I have asked you to perform no shortage of questionable, cruel, and depraved acts, all for my and the Empire's benefit, but..." she trailed off, visibly struggling for words.

"Whatever it takes," Byleth said.

Edelgard stopped. "Pardon?"

"Whatever it takes to achieve my goals, to bring about a better future not just for the Empire, but all of Fódlan," Byleth continued. "Let them spit on my legacy, forsake my methods, forever paint me in history as a heartless monster, so long as this sorry state of affairs joins me in the pages as well."

Edelgard scowled. "Using my own words against me..."

"Edelgard, this could be an ideal solution to my Thirst," Byleth said, unaffected. "You and Hubert will no longer have to burden yourselves with trying to find victims for me to feed on, and conceal that dark business besides. It may only be one less problem to consider, _but,_ it only takes one major slip for all your plans to come crashing down.

"Do you really wish to dismiss such potential benefits outright, simply because it crosses lines you had not thought of before…?"

Edelgard opened her mouth, before she closed it, then sheepishly looked down. "… You make excellent points, Byleth, and I find I cannot, and should not refuse them." She sighed, then looked back up, "We may attempt this… solution to your Thirst as soon as possible. I assume you already have an idea of how we might go about this, exactly?"

Byleth nodded. "You remove your clothes, lay in a comfortable position on your bed, and then I feed on your blood."

"And how precisely will you be feeding?" Edelgard asked warily. "There will be no teeth nor _biting_ involved, would there?"

Byleth shook her head. "Absolutely not. Only licking, sucking, and possibly some use of my fingers, unless more is requested," she said as she held a hand up, her claws already transformed into regular, human nails.

Edelgard grabbed it and pulled it up to her face, inspecting them closely. "File your nails down to complete bluntness, wash your hands thoroughly, then rinse out your mouth," she said as she let go. "I'll not have myself injured nor infected by this experiment."

"At once," Byleth said, bowing before she disappeared once more.

Edelgard stared at the empty space, before she looked down at the floor. "What have I gotten myself into now…?" she wondered.

Soon, she was laying nearly naked on her bed, wearing only the smallclothes of her chest, finding a comfortable where she could sit with her legs spread. "These sheets will have to be disposed of afterward," Edelgard thought as she leaned back, tested the comfort of the pillows stacked behind her and against the headboard. "Burned, ideally, for both the physical evidence and what will soon transpire on them."

A few moments later, Byleth reappeared, now dressed in commoner's sleepwear. She greeted Edelgard, then showed off both hands, every nail now meticulously filed down nearly to the quick, their edges rounded off.

"Good," Edelgard said, nodding. "You may…" she hesitated for a moment "… commence whenever you are ready."

Byleth nodded, climbed into Edelgard's bed, and proceeded to kneel down before her, her hands gently holding onto Edelgard's thighs, and her head held between her legs.

Edelgard felt a heat growing in her cheeks, quickly forced herself to calm down. "Ugh, don't feel this way about this; this is _disgusting_ , and will only get more so,” she thought to herself.

"Are you having second thoughts, Edelgard?" Byleth asked.

"Just unexpected reactions," Edelgard replied.

"Such as getting aroused?" Byleth asked, expression and tone still blank.

Edelgard choked, and looked indignant.

"It's nothing to be ashamed of, nor is it surprising at all," Byleth said. "If not for our primary intent, this would be a very intimate, sexual act. It'd be more surprising if you did not become excited, honestly."

"Are you going to drink my blood or not?" Edelgard snapped. "Or was this all just an elaborate scheme to debase me for your entertainment?"

"I am, and it's not," Byleth replied coolly. "I am simply wondering if I should seek to pleasure you as well as feed."

"P-Pleasure me…?" Edelgard stammered. "Byleth, you are a demon of war and combat, are you not?"

"I am," Byleth said, nodding. "But that does not mean I am unable to serve you in other capacities, such as sexually."

"… Why are you suddenly speaking of such matters?" Edelgard asked, trying to look suspicious.

"Because even if this is primarily for my benefit, it would not hurt if we both gain something from it, would it?" Byleth replied.

Edelgard stared at her, before she sighed, and said, "Fine. Do as you please. Let's just get this over with, we've wasted enough precious time already."

"As you wish, Edelgard," Byleth said. "Please, just relax, and do not hesitate to guide me, or ask for me to stop at any time."

"Oh, _believe me,_ you'll _know_ if you've done something wrong..." Edelgard grumbled as she laid back.

To her surprise, Byleth did not go straight for her netherlips, stained red with old blood and dripping with a fresh flow; instead, her hands roamed along her inner thighs and the backs of her knees, trying all manner of styles of stroking, caressing, and some holding.

"Are-Are you not going to feed…?" Edelgard asked.

"Later," Byleth said.

"What are you even--" Edelgard let out a high-pitched squeak, a hand flew over her mouth as her cheeks began to burn.

Byleth did not say anything, just stroked the back of Edelgard’s knee in the same manner as earlier, eliciting another squeak. She continued on with her exploration, eliciting more and more undignified whimpers and squeals, till Edelgard was barely able to muffle them even with both hands clapped over her mouth, resist the urge to squirm and shiver at her touch.

Byleth stopped, and looked up at Edelgard, the hard line of her mouth slowly curled into a small, but noticeable smile. "You're enjoying this," Byleth said.

There was no cruel amusement, like there would have been if Byleth were teasing Edelgard. There was no hint of surprise, like there would have been if she found this unexpected. There was just the flat and plain tone Byleth took for most every single word that came out of her mouth, like she were stating an irrefutable, obvious fact such as the sky was blue, water was wet, or Edelgard was the crown princess of Adrestia.

And to be fair to her: Edelgard _was_ enjoying this.

Byleth turned her head back down, continued to search for Edelgard’s weak spots. Unlike her enemies, however, she was deliberately going slow, taking her time, pointedly avoiding straying anywhere near Edelgard's netherlips, now wet with arousal as well as blood.

"Byleth..." Edelgard whispered, shivering and shaking as Byleth gently caressed the back of her knee again. "Are you ever going to move on from this?"

Byleth stopped, looked up at her, and asked, "Do you want me to do so now?"

"Y-Yes," Edelgard replied. "I didn’t plan on devoting the rest of the day to this..."

Byleth hummed. "As you wish, Edelgard,” she said. Her hands moved to just before Edelgard's knees, gently keeping her legs spread; Edelgard felt her breath hitch as Byleth began to lean in… then plant a soft, warm kiss on her left inner thigh.

Edelgard yelped and shivered from the sensation. Byleth began a trail of kisses leading up, getting closer and closer she came to Edelgard's netherlips, her pace slowing gradually slowing down to a crawl. Edelgard trembled in anticipation, closing her eyes as Byleth was almost _there_ …

… And then Byleth pulled away, beginning the process all over again on her right thigh.

Edelgard began to complain, was quickly silenced as Byleth attacked one of her weak spots, again, forced forced her to clap her hands over her mouth to muffle the undignified noises. Edelgard glared at her, Byleth continued on, unhurried and unaffected.

Edelgard was squirming by the time Byleth neared her netherlips once more; her breath hitched as Byleth moved to bury her face right into her groin, so close she could already feel her hot breath on her skin…

… But again, she stopped.

Edelgard thought of yelling at her, before twin pillars of black smoke shot out from Byleth’s head, solidifying into two long, solid demonic horns. "Please hold onto more horns,” she said, “it will give you a better, firmer, more comfortable grip on my head than if you were clutching onto my hair."

Edelgard stared. Rarely had Byleth ever exposed her horns since she'd first summoned her, unless she needed them to maim or murder someone. "And now I am to hold her down by them…?" she thought. It was making her heart race—quite a bit more than she'd like to admit.

"Edelgard?" Byleth asked.

Edelgard slowly wrapped her fingers around Byleth's horns. They were solid, cool to the touch like long-dead ashes, smooth like volcanic rock, except for the regularly spaced ridges. And with the angle they curved back at, they were really quite easy and comfortable to grip.

“Ready?" Byleth asked.

"Yes," Edelgard replied, before carefully pulled Byleth's face into her groin, till she could feel her warm lips pressed right up to her wet netherlips, her nose buried into the patch of fuzzy white hair just above it. She was about to order Byleth to start feeding, instead let out as an embarrassing shriek as Byleth pressed her tongue flat against her folds.

More and more undignified noises spilled out of Edelgard as Byleth began to slowly run her tongue up, taking in as much of her blood as possible. She reached the top and pulled her tongue back into her mouth, let out a deep, throaty purr like a large predator.

“Is this satisfying your Thirst…?" Edelgard whispered.

"Not yet,” Byleth replied, "definitely need more—much more."

"Don’t hesitate to get it, then…” Edelgard mumbled.

“I won’t,” Byleth said. Soon, she settled into a calm, unhurried pace, stopping only when there was a particularly strong flow she could let spill right onto her tongue. "Ugh…" Edelgard she thought as she heard Byleth eagerly lapping up and swallowing her blood, her little noises of pleasure, "this all so… _confusing.”_

Byleth seemed to ignore or not care about Edelgard's increasingly frantic squirming, her cries and whimpers, or her ever tightening grip on her horns. Then she suddenly stopped, lifted her head up, and said something.

Edelgard did not catch it, distracted by the sight of Byleth's lips wet and glistening with her blood and arousal, the excess dripping down her chin, the supernatural, alluring glow of her eyes.

"Edelgard, shall I make you come?" Byleth repeated.

Edelgard blinked. "I—that's not really necessary, Byleth!" she stammered.

"Are you sure?" Byleth asked. "Many find it torture, prolonged pleasure without release."

"I'm sure," Edelgard said, trying to keep her voice level. "You focus on your satisfaction, not mine," she said, before she pulled Byleth's head back between her legs. Byleth resumed immediately, Edelgard bit her lip and suppressed a cry—that brief break made the sensation so intense again. She thought of changing her mind, decided instead to take slow, deep breaths, relax her death-grip on Byleth's horns.

"Calm. Calm. Be calm," Edelgard thought as yet more pleasant shivers and shocks ran up her spine. "You have endured and survived far worse than this in the past, you will do so again now!"

Not even five minutes later, her resolve crumbled into dust, and she all but yanked Byleth's head from between her legs. "Shall I make you come?" Byleth asked.

Lip bit, cheeks aflame, eyes desperate, Edelgard nodded.

Byleth moved her mouth over Edelgard's throbbing clit, planting one more gentle kiss before she wrapped her lips around it, began to suck and lick. The sudden surge of stimulation was so intense Edelgard almost jumped and yanked Byleth’s head up, but Byleth’s hands on her thighs and her strength kept her in place, until everything went white.

Edelgard turned into a squealing, whimpering mess, what few words she could manage being attempts at saying Byleth’s name and little exclamations of pleasure, hips bucking wildly as her arousal gushed from her netherlips, knuckles turning white from how tightly they were gripping Byleth’s horns. Her orgasm faded, Edelgard near-instantly fell limp against her pillows, breathing heavily, and staring up at the ceiling in a daze.

All was quiet for several minutes, before Byleth lifted her head up, and asked, "Shall I continue?"

Edelgard groaned. "No, no more… please, no more..."

Byleth nodded. "As you wish, Edelgard," she said, before she pulled away, sat back on her knees, and licked the excess blood and arousal off her fingers.

"Did this satisfy your thirst, Byleth?" Edelgard asked.

Byleth shook her head. "No, I don't think it did. This type of blood is not nearly as rich in vitae, nor could you supply enough of it, I believe."

Edelgard sighed. "Well, I suppose we at least we know for sure now…"

Byleth hummed in agreement.

"We really shouldn't do this again..." Edelgard mumbled.

Byleth nodded. "As you wish."

"And we need to set this entire bed on fire," Edelgard continued."The sheets, mattress, the frame—everything."

"That seems a little extreme," Byleth said.

"No, it is not," Edelgard grumbled. "What we have done here is absolutely _unspeakable._ Just as the memory will never fade, so will the evidence remain, until every last piece is consigned to the flames..." she yawned, and the rest of the tirade came out as an exhausted, unintelligible grumble.

"You're tired, Edelgard," Byleth said as she crawled forward, began to rearrange the pillows and Edelgard to a relatively more comfortable position. "Sleep."

Edelgard could only make another grumble of protest, before all the sleep deprivation was finally caught up to her. "Sheets… blood..." she mumbled as her eyes fell shut, she couldn't find the strength to open them again.

"I’ll take care of it, Edelgard," Byleth said, just before Edelgard fell asleep.

* * *

It no longer fazed Dorothea, Byleth's ability to appear behind her as if from thin air. Neither was she bothered by her curt and mysterious orders, nor the cryptic warning that she be prepared for something quite disturbing, but maintain her usual discretion and decorum still.

She had thought that desensitization would extend to whatever mess Byleth had made this time.

She was wrong.

Dorothea began to feel unease when Edelgard did not respond to her gentle knocks, nor her softly calling out her name. Edelgard was a perilously light sleeper, and even neck-deep in paperwork and official matters, she would still poke her head out if something or someone important enough came calling, such as her. When much more forceful knocks and insistent calls did not do the trick, Dorothea was certain that something was _terribly_ wrong.

"Do you require assistance, Lady Arnault?" one of the guards outside Edelgard's door asked.

"Not at all!" Dorothea replied, forcing a convincing smile. "Edelgard's been so busy these past few weeks, I'm certain she's just fallen into a deep sleep from exhaustion. If I find need of your strength, just listen for my screaming, okay?"

The guard nodded, not even cracking a smile. "As you wish, Lady Arnault."

At that, Dorothea used copy of her key, and slipped into Edelgard's room. She shut and locked the door behind her, and turned around to Edelgard, whereupon her pleasant smile quickly turned into open-mouthed horror.

"E-Edie…!" Dorothea stammered, her eyes wide, her voice and whole body shaking, just barely keeping herself together. "What in the world happened?!"

Edelgard stirred awake, looking sleepy and annoyed, before realization hit her and she was nigh instantly awake. "Dorothea!" she cried. "What are you doing here?!"

"Byleth asked me to! Now please, tell me what happened…?!" Dorothea asked, barely keeping from screaming.

Edelgard opened her mouth, before she stopped, and suddenly turned away, her cheeks burning red.

For a moment, Dorothea was confused, until a spark gleamed in her eyes.

Edelgard noticed. "Dorothea…" she started.

Dorothea reexamined the way Edelgard was positioned, her conspicuous lack of clothing, and where most of the bloodstains on the sheets were concentrated. "Ah…" she said, nodding and smirking, "I get it."

Edelgard's cheeks burned ever brighter. "Dorothea--!" she started, holding out her hands.

"No, no, no! No need to worry nor panic, Edelgard!" Dorothea said, waving her off. "Believe me, my lips are sealed, and no word of this will ever leak outside these four walls. Now, onto more important matters: shall we get you off those bloody sheets? I'm going to draw a bath for you also, Edie, you really rather need one."

Edelgard opened her mouth, looking desperate, before she sighed, and quietly got off her bed.

Dorothea carefully began to strip the sheets off. "Oh, and Edie? I have two things I need to tell you about, also."

"Go ahead, Dorothea," Edelgard said as she stood to one side, grabbing a clean cloth off her dresser and pressing it between her legs.

"First, we just received a message from Hubert,” Dorothea said as she began to wrap up the sheets in a cheaper cloth. “I don't know what it said, but Byleth and a good number of soldiers set off in a hurry, which is why I’m here instead of her."

Edelgard nodded, and made a mental note of it. "And the second?"

"You should _really_ go see a healer as soon as possible, and send Byleth a message to do the same," Dorothea hummed. "Wouldn't want either of you to get a serious infection from some _unorthodox_ fun, would we?" she continued, winking.

Edelgard made a choked noise. She opened her mouth, before she shut it, and hung her head. "We will, Dorothea..." she mumbled.


End file.
